Table 2.

Comparison of phenotypic characteristics between the L and S variantsa

PhenotypeDescriptionsb
L variantS variants
Colony shapeLarge, flat, irregular Small, rounded
Adherence to surfaces + ++
Hydrophobicity + ++
Initiation of biofilm formation ++
Flagella + +
Polar pili + ++
Motility:
 Swimming ++ +
 Swarming +
 Twitching ++ +
Chemotaxis +
Exoproducts
 Pyoverdine + ++
 Pyocyanin + ++
 Alginate + +
 Elastase++ +
 Rhamnolipids ++ +c
Sensitivity to H2O2 stress +++
  • a The L variant predominates on agar plates or in agitated liquid cultures; S variants predominate in biofilms or in static liquid cultures.

  • b —, absence of phenotype; +, presence of phenotype; ++, expression of phenotype more pronounced than +.

  • c Rhamnolipid production is significantly lower than in the L variant for the S2 variant only.